A prior art process is set forth in the International Patent Application having the publication number WO 93/07081. That process describes typographical labeling or a caption on the inner sides of books borne by a conveying device. In the conveying device, the books are borne in the folded state, the fold being located parallel to the conveying direction, and the two halves of the respective printed products being arranged to the left and right of the conveying device and hanging downwards therefrom. A guide cord is located beneath the conveying device and serves for retaining the two halves of the printed products at a slight distance apart from one another. Adjoining one end of the cord is a plough-like part, which turns one half of the folded printed product increasingly into a horizontal position from the vertical position, the typographical labeling being carried out in the border region of the page of the horizontally guided half of the books by a printing head which is fitted in the region of the delivery end of the plough.
This known process and apparatus maintains as constant as possible, the acceleration of the half of the printed products which are moved from the vertical position into the horizontal position, since a higher operating speed is thereby expected.
It may be problematical, in the case of this arrangement, that, despite the constant acceleration, conveying the printed products with the fold parallel to the conveying device leads to the air which is displaced and, as a result, being forced between the pages of the printed products and causing them to flutter, especially when a higher circulating speed of the conveying device is desired.
The prior art also includes the integrated inkjet system of the company Ferag AG, Hinwil/Switzerland, which permits typographical labeling of border regions of individual pages of a printed product, but has not yet been designed to permit opening of folded printed products for typographical-labeling purposes.